Thiazolylthiocyclohexanones



United tates Patent 3,051,716 THIAZOLYLTHIOCYCLOHEXANONES John J. DAmico, Charleston, W. Va., assignor to Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware No Drawing. Filed Oct. 18, 1960, Ser. No. 63,254 11 Claims. (Cl. 260-302) The present invention relates to thiazolylthiocyclohexamones and to methods for their preparation. These compounds, heretofore unknown, have a number of useful applications. They are valuable intermediates and accelerate vulcanization of rubber.

The products of the invention have the general formula where T represents a thiazolyl group. As typical examples of thiazolyl radicals there may be mentioned 4-ethylthiazolyl,

4-methylthiazolyl, 4,5-dimethylthiazolyl, 4,5-diethylthiazolyl, 4 methyl-5-acetylthiazolyl, 4-methyl-5-carbomethoxythiazolyl, 4-methyl-5-carboethoxythiazolyl, 4-carboethoxythiazolyl, 4-methyl-5-carbamylthiazolyl, 4-methyl-5-phenylcarbamylthiazolyl, benzothiazolyl, 4-ethylbenzothiazolyl, 7-methylbenzothiazolyl, 4-methylbenzothiazolyl, S-methylbenzothiazolyl, G-methylbenzothiazolyl, 4-chlorobenzothiazolyl, 4-methyl-6-chlorobenzothiazolyl, 6-chlorobenzothiazolyl, 6rphenylbenzothiazolyl, 4-phenylbenzothiazolyl, 4,5-dimethylbenzothiazolyl, 4,6-dimethylbenzothiazolyl, 4-methoxybenzothiazolyl, S-methoxybenzothiazolyl, 6-methoxybenzothiazolyl, 4-methoxy-6-chlorobenzothiazolyl, 4-ethoxybenzothiazolyl, S-ethoxybenzothiazolyl, 4,6-dimethyl-7-chlorobenzothiazolyl and 4,6-dimethyl-5,7-dichlorobenzothiazolyl. f

It was discovered that compounds conforming to the H -=0 a I 7 OH- Q Q 1A 1H ice In this connection, the odor of ammonia was detected. The compounds are also obtainable by condensation of 2- chloroor 2-bromocyclohexanone with an alkali salt of mercaptothiazole.

The following examples illustrate the preparation of the new compounds in detail but are not to be taken as limitative of the invention.

EXAMPLE 1 A charge consisting of 100 parts (0.548 mole) of 2- benzothiazolesulfenamide, 58.8 parts (0.6 mole) of cyclohexanone and 400 ml. of ethyl alcohol containing 30 ml. of 2 N sodium hydroxide was heated with stirring at -80 C. for 1 hour. After cooling to 5 C., 400 ml. of cold water was added and stirring continued for 30 minutes. The oily-water reaction mixture was poured into an evaporating dish and allowed to stand for one week. The resulting semi-solid was filtered, washed with 200 ml. of heptane and dried on a porous plate. After recrystallization from ethyl alcohol the 2-(2-benzothiazolylthi-o)cyclohexanone melted at 92-93 C. It was a tan solid obtained in 79.1% yield. Analysis gave 5.4% nitrogen and 24.3% sulfur compared to 5.3% nitrogen and 24.4% sulfur calculated for C H NOS EXAMPLE 2 The above described material was also prepared by the following method: To a stirred solution of 86 parts (0.5 mole) of 97% mercaptobenzothiazole, 33 parts (0.5 mole) of potassium hydroxide, 500 ml. of acetone and 10 parts of water was added in one portion 66.8 parts (0.5 mole) of 2-chlorocyclohexanone and the stirred reaction mixture heated at 5056 C. for 4 hours. After 5.3% nitrogen and 24.4% sulfur calculated for A mixed melting point with the compound of Example 1 was 9293 C. and the infrared spectra of the two were superimposable, indicating the compounds were identical.

EXAMPLE 3 To a stirred solution of 100.8 parts (05 mole) of 5chloromercaptobenzothiazole, 31.5 parts (0.5 mole) of 90% potassium hydroxide, 500 ml. of acetone and 10 ml. of water was added in one portion 66.8 parts (0.5 mole) of 2-chlorocyclohexanone and the reaction mixture heated at 5056 C. for 4 hours. After cooling to 10 C. the reaction mixture was added to 2000 grams of icewater and then stirred at 010 C. for 1 hour. The precipitate was collected by filtration, washed with water until neutral to litmus and air-dried at 25-30" C. 2-(5- chloro-2- benzothiazolylthio)cyclohexanone was obtained in 90% yield as a tan solid. After recrystallization from heptane it melted at 9293 C. Analysis gave 4.7% nitrogen and 21.5% sulfur, the calculated values for C H ClNOS EXAMPLE 4 In the procedure of Example 3, 105.5 parts (0.5 mole) of 6-ethoxymercaptobenzothiazole was substituted for 5- chloromercaptobenzothiazole. After cooling to 10 C.,

500 ml. of water was added. The reaction mixture was extracted with 500 ml. of ethyl ether, the ether solution washed with water until neutral to litmus and dried over sodium sulfate. The ether was removed. in vacuo at a maximum tenlperaturei of To a stirred solution of 101.6 parts (0.5 mole) of ethyl oxy'z'bePzothlazolylthlo)cyclohfixanonti was obtalned 2-mercapto-4-methylv5-thiazolecarboxylate, 31.5 parts (0.5- 89.5% yield as a dark amber viscous o1l. Analysis g mole) of 90% potassium hydroxide, 500 m1. of acetone 3 mtmgen and 202% Sulfur compared 2 to 45% and ml. of water was added in one portion 66.8 grams mtrogen 209% Sulfur calculflted for H F (0.5 mole) of 2-chlorocyclohexanone and, the mixture T functlonal Canbonyl gTOuR lmparis reactlvlty of a 10 stirred at25-30" C. for 6 hours. Then 400 ml. of water typlcal k The products yleld oxlmejs Q and 500 ml. of ethyl ether were added and the mixture ment Wlth salts hyclroxylamme Reductlon Witt} 9 stirred for minutes. 2-(5-carboethoxy-4-methyl-2-thim l q ylelds 2'hydroxycyclohexylthmthla' azolylthio)cyclohexanone was isolated as described above. zoles. As mdicated above the products per se accelerate An oil was obtained in 34% yield. Analysis gave 45% vulcamzanon of rubber" 15 nitrogen and 21.4% sulfur compared to 4.7% nitrogen The products of the above examples were demonstrated and 214% Sulfur calculated for C13H17NO3S2 to be rubber vulcanization of accelerators by testing in the following tread stock: EXAMPLE 7 St pk A B C In the procedure of Example 6, 65.7 parts (0.5 mole) O of 4-methy1-2-mercaptothiazole was substituted for the P t b ht thiazole of that example and the reaction mixture heated at s ywelg at 5056 C. for 4 hours. Upon isolating as described 2-(4-methyl-2-thiazolylthio)cyclohexanone was obtained iifif rubber 28 28 28 in 76.6% yield asan amber oil. Analysis gave 5.8% nig g g trogen compared to 6.2% calculated for C H NOS Saturated hydrocarbon softener 3 3' 3 As illustrative of accelerating properties, vulcanizable g fl f compositrons were compounded compnsmg 2-(5-Ohloro-2-benzothiazolylthi0)-cyclohexanone 0.5 2-(2-Benzothiazolylthio) cyclohexanone. 0.5 2-(G-Ethoxy-2-benzothiazolylthio)-cyr-1nhpwnrmp 0.5 30 Stock 1) E F The stocks Were cured in the usual manner by heating Parts by Welght in a press for 60 minutes at 144 C. The physical properties of the vulcanizates are set forth below: fig gggi f rubber g8 28 Z a 5 5- 5 Table I si jga riz ao id 3 3 3 Saturated hydrocarbon softener 3 3 3 Sulfur. 2.5 2.5 2.5 Modulus of Antioxidant 1 1 1 Elastlcltym Tellsllefit 2-(5-Aeetyl-4-methyl-2-thiazolylthio)-cyclohexanone 0.5 Stock l s/ at ak In 2 5 Carboethoxy 4 Methyl 2 thiazolylthio) Elongatlon of lbs/1n. 40 c plnhexannne 0.5 2-(4-Methyl-2Jhiaz0lylfl1io)cyrlflhexannnp 0. 5

1,270 2, 410 1,190 2,600 The stocks were cured 1n the usual manner 1n a press for 1,180 2,220 60 minutes at 144 C. The physical properties of'the vulcanizates and resistance of the unvulcanized composi- The resistance of the stocks to prevulcanization (scorch) tion to scorch are set forth below: was evaluated by means of a Mooney plastometer. The time required for incipient vulcanization or scorch was Table HI taken at the point on the plasticity curve when the plasticity began to rise continuously and reached an arbitrary Modulus r Tensile Scorch value of 10 unit points above the minimum value. Stock at Elongation lbs/in. Percent 135 C Table II of300% Mooney scorch in Stock: mins. at 135 C. 55 n 1,720 3,480 530 7.9 A 115 as 181 B 13'.8 C 17.6

EXAMPLE, 8 EXAMPLE 5 As a further specific embodiment of the invention, a solution was prepared comprising 43.4 parts (0.25 mole) of Z-mercapto-4-methyl-5-thiazolyl methyl ketone, 15.8 parts (0.25 mole) of 90% potassium hydroxide, 250 ml. of acetone and 5 ml. of water. This solution was agitated while adding in one portion 33.4 parts (0.25 mole) of 2- chlorocyclohexanone. The reaction mixture was heated at 50-56 C. for 4 hours, then cooled to 25 C. A solution of 300 ml. of ethyl ether in 250 ml. of water was; added and the mixture stirred for 15 minutes. solution was washed With water until neutral to litmus and dried over sodium sulfate. The ether was removed in vacuo at a maximum temperature of 8090 C./1-2 mm. 2-(5-acetyl-4-methyl 2 thiazolylthio)cyclohexanone was gave 4.9% nitrogen and 23.9% sulfur compared to 5.2% nitrogen and 23.8% sulfur calculated for C H NO S EXAMPLE 6 To a stirred solution of 87.0 parts (0.5 mole) of 2-mer-- capto-4-methyl-S-thiazolecarboxamide, 31.5 parts (0.5 mole) of 90% potassium hydroxide, 500 ml. of, acetone and 10 ml. of water was added inone portion, 66.8 parts (0.5 mole) of 2-chlorocyclohexanone and the reaction. mixture heated at 50-56 C. for 4 hours. After cooling to 25 C., the reaction mixture Was added to 2,000 grams of ice-water and the solution stirred at 0-10. C. for 1 hour. The precipitate was collected by filtration, washed The ether at 165-167 C. Analysis gave 10.6% nitrogen and 23.9%

sulfur compared to 10.4% nitrogen and 23.7% sulfur obtained in 83.5% yield as aw dark amber oil. Analysis calculated for C H N O S 5 EXAMPLE 9 Substituting 125 grams (0.5 mole) of 2-mercapto-4- methyl5-thiazolecarboxanilide for the thiazole employed in Example 8, the solution of the reaction product in 2000 grams of ice-water was stirred at -10" C. for 3 hours. 2 (4 methyl phenylcarbamylthiazolylthio)cyclohexanone was obtained in 92% yield as a white solid. After recrystallization from ethyl alcohol it melted at 132133 C. Analysis gave 8.4% nitrogen and 18.7% sulfur compared to 8.1% nitrogen and 18.5% sulfur calculated for 1'1 1s 2 2 2- Further illustrative of the properties of the thiazolylthiocyclohexanones of this invention, natural rubber stocks were compounded comprising Stock- G H Parts by weight Smoke sheets rubber 100 100 Carbon black 50 50 Zinc oxide 5 5 Stearic acid 3 3 Saturated hydrocarbon softener 3 3 Sulfur 2. 5 2. 5 Antioxidant 1 1 2 (5 Carbamyl 4 methylthiazolylthio)cyc1o hexan one 0. 5 2-(4 Methyl Sphenylcarbamylthiazolylthio)-eycloheranrmo 0. 5

The stocks were cured for 60 minutes in a press at 144 C. The test results obtained were as follows:

Table IV Stock G H Modulus of Elasticity in lbs/in. at 300% elongafirm 1, 000 1, 120 Tensil at Break in lbs/in} 2, 060 2, 410 Ultimate Elongation, Percent 500 500 Mooney Scorch at 135 0. in minutes 16. 9 12.0

Although the invention has been illustrated by numerous specific embodiments, it is not limited thereto. For example, the thiazolylthiocyclohexanones may be used for the acceleration of other types of sulfur-vulcanizable rubbers. These rubbers comprise natural rubber in its various forms, as for example latex, crepe, smoked sheets, gutta-percha, balata and cyclo rubbers. The new compounds are applicable generally for acceleration of natural and synthetic elastomers, as for example polybutadiene, polyisoprene and polyisobutylene polymerized with a small proportion of a diolefin.

It is intended to cover all changes and modifications of the examples of the invention herein chosen for purposes of disclosure which do not constitute departure from the spirit and scope of the invention.

What is claimed is:

1. A 2-(2thiazoly1tl1io)cyclohexanone of the formula where T is a member of the group consisting of 4-(lower alkyl)-2-thiazolyl, 4-(lower alky1)-5-(lower carboalkoxy)- Z-thiazolyl, 4,5-di-(lower alkyl)-2-thiazolyl, 4-(lower carboalkoxy)-Z-thiazolyl, 4-(lower alkyl)-5-acetyl-2-thiazolyl, 4-(lower alkyl)-5-carbamyl-2-thiazolyl, 4-(lower alkyD-S-(n-phenylcarbamyl)-2-thiazolyl, 2-benzothiazolyl, monochloro-Z-benzothiazolyl, monoand di-(lower alkyl)- 2-benzothiazolyl, mono-(lower alkyDmonochloro-Z-benzothiazolyl, mono-(lower alkoxy)-2-benzothiazolyl, mono- (lower alkoxy)monochloro-Z-benzothiazolyl, phenyl-Z- benzothiazolyl, di-(lower alkyl)monochloro-2-benzothiazolyl and di-(lower alkyl)dichloro-Z-benzothiazolyl.

2. 2-(2-benzothiazoly1thio) cyclohexanone.

3. 2-(5-chloro-2-benzothiazolylthio) cyclohexanone.

4. 2-(6-ethoxy-2-benzothiazolylthio)cyclohexanone.

5. 2-(5-acetyl-4-methyl-2-thiazolylthio) cyclohexanone.

6. 2-(5-carboethoxy-4-methyl-2-thiazolylthio)cyclohexanone.

7. 2-(4-methyl-2-thiazolylthio) cyclohexanone.

8. 2-( S-carbamyl- 4 -methyl 2 thiazolylthio) cyclohexanone.

9. 2 (4-methyl-5-n-phenylcarbamyl-Z thiazolylthio) cyclohexanone.

10. Method of making a 2-(2-thiazolylthio)cyc1ohexanone which comprises heating a compound of the formula TS-NH where T is a member of the group consisting of 4-(lower alkyl)-2-thiazolyl, 4-(lower alkyl)- 5-(lower carboalkoxy) -2-thiazolyl, 4,5-di(lower alkyl)-2- thiazolyl, 4-(lower carboalkoxy) -2-thiazolyl, 4-(lower alkyl)-5-acetyl-2-thiazolyl, 4-(lower alkyD-S-carbamyl-Z- thiazolyl, 4-(lower alkyl)-5-(n-phenylcarbamyl)-2-thiazolyl, 2-benzothiazolyl, monochloro-Z-benzothiazolyl, monoand di-(lower alkyl) -2-benzothiazolyl, mono- (lower alkyl)monochloro-Z-benzothiazolyl, mono-(lower alkoxy)-2-benzothiazolyl, mono-(lower alkoxy)monochloro-2-benzothiazolyl, phenyl-Z-benzothiazolyl, di- (lower alkyl)monochloro-Z-benzothiazolyl and di-(lower alkyl) dichloro-Z-benzothiazolyl with cyclohexanone in the presence of hydroxyl ion and isolating a 2-(2-thiazolylthio) cyclohexanone.

11. The method of claim 10 where T is 2-benzothiazolyl.

No references cited. 

1. A 2-(THIAZOLYLTHIO)CYCLOHEXANONE OF THE FORMULA 